Interlocking control apparatus



Nov. 8, 1938 H. A. THOMPSGN INTERLOCKING CONTROL APPARATUS Filed July 51, 1935 INVENTOR 11 mm A'I'hompsan B ATTORNEY HIS Patented Nov. s, 1938 2,136,159

UNITED STATES PATENT OFFICE INTERLOCKING CONTROL APPARATUS Howard A. Thompson, Edgewood, Pa., assignor to The Union Switch 8; Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application July 31, 1935, Serial No. 34,042

11 Claims. (Cl. 246-3) My invention relates to interlocking control ap- Each of the signals S, as here shown, is of the paratus for railway track switches and signals semaphore type. They may, however, be of any in a railway switching or interlocking layout. other suitable construction.

One feature of my invention is the provi- Switch control device F is controlled by pole- -5 sion of means for safeguarding the operation changing contacts I and 8 of a lever relay 1) 5 of the apparatus after a switch has been irreii a stick locking relay L is energized, or by polar gularly operated as, for example, by hand. contacts of a polarized switch control relay w The apparatus of my invention is an improveif relay L is deenergized. ment over that disclosed in the copending ap- Lever relay '0 is controlled by a contact 33 of m plications Serial No. 416,061, filed December 23, a switch lever V Lever V has two positions, 10 1929, by Howard A. Thompson for Multiple a normal position 11 and a reverse position r. control apparatus, and Serial No. 695,294, filed Contact 33 is closed only when lever V is in October 26, 1933, by Allen 81 Thompson for Inthe 1 position. terlocking control apparatus. Locking relay L is controlled by switch control 15 I will describe two forms of apparatus emrelay w, by lever relay 1), by track relay T and 15 bodying my invention, and will then point out by an approach locking relay P. the novel features thereof in claims. Relay w is controlled in multiple with control In the accompanying drawing, Fig. 1 is a device F. Relay w may be so constructed that, diagrammatic view showing one form of apparawhen it becomes deenergized, its polar contacts tus embodying my invention, in which a switch will remain in the position to which they were 20 is operated by an electric motor. Fig. 2 shows last operated.

a modification of this form of apparatus, also An indicator which is here shown as an elecembodying my invention, in which a switch is tric lamp 6 is contro ed by re ay L and y a operated by a motor of the fluid pressure type. polarized switch indication relay K. Similar reference characters refer to similar Approach lockin r l y P is controlled y 25 parts in each of the views. signal contacts H and I8, by track relays T, and

Referring first to Fig. 1, the reference characby a thermal relay R. ters l and I designate the track rails of a stretch Thermal relay R comprises a heater element 23 of railway track Y which is divided by insulated and a contact 22 which closes only after element joints 2 into sections BC and CD. Each of 23 has been energized for a given period of time. 30 these sections is provided with a track circuit, erma re y R S ContrOlled by Signal Contacts comprising a battery 3 connected across the rails I1 and 3 a d by a back Contact of relay adjacent one end of the section, and a track re- Switch indication relay K is controlled by polelay, designated by the reference character T Changing Contacts 3| and 32 which are Operated 35. with a distinguishing exponent, connected across by switch W. 35

the rails adjacent the opposite end of the section. Each of the signals S is controlled by a slow- Located in section CD is a switch W for conrelease relay which is designated by the refernecting track Y with a second track Z. Switch ence character H with an exponent correspond- W is operated by an electric motor G which is ing to that of its signal, and by a signal lever governed by a control device F. Motor G com- V Lever V has a normal position 111. and 40 prises an armature 4 and a field winding 6. a reverse position r for controlling signals S A contact 5 is shown in the motor circuit adand S", and may also have a reverse position n jacent the field winding 6. This contact may be to the left for controlling signals for the oppomanually opened in order to deenergize motor G site direction of traffic movements over switch when it is desired to move switch W by hand. W. Contact 34 of lever V for controllin S na s 45 At point C a signal S is shown for governing S and S is closed only when lever V is in its 1' eastbound trafiic movements, that is, traflic position. movements from left to right, as shown in the Each of the relays H is controlled by lever drawing, over switch W in the normal position relay 0 when relay L is energized, and is conin which it is shown. A second signal S is also trolled by relay w when relay L is deenergized. shown for governing eastbound traffic move- Relay H is also controlled by relay K energized ments over switch W in the reverse position to in the normal direction, and relay I-l. is controlled track Z. Signals S and S operate contacts IT by relayK energized in the reverse direction. and 18, respectively, each of which is closed only In each of the two figures of the drawing, the when the corresponding signal is indicating stop. contacts operated by the various relays, levers,

switch W, or signals S are identified by numbers, such numbers having distinguishing exponents when the contacts are not shown adjacent the device by which they are operated. The exponent for each of these contact numbers comprises the reference character and exponent for the device by which it is operated. For example, the exponent w for contact 9' shown in the circuits for relay L comprises the reference character w for switch control relay w which operates contact 9 Similarly, exponent T for contact 2S in the circuits for relay L comprises the reference character T and its exponent 2 for track relay T which operates contact 26'.

In Fig. 2 switch W is shown operated by a fluid pressure mechanism M. This mechanism is controlled by normal and reverse magnets an and r9", respectively.

Normal magnet 1111 is controlled by a back con tact of relay 1: when relay L is energized, and is controlled by a normal contact of relay to when relay L is deenergized. Reverse magnet rr is controlled by a front contact of relay when relay L is energized, and is controlled by a reverse contact of relay 10 when relay L is deenergized.

Relay w in Fig. 2 is controlled similarly to relay in in Fig. 1, except that in Fig. 2 it is shown connected with only one of the switch control wires at a time, whereas in Fig. 1 it is shown connected across the switch control wires. For the arrangement in Fig. 2, the winding of relay in is provided with a mid-tap which is constantly connected to the negative terminal of a source of energy. The two portions of the winding of relay w in Fig. 2 are therefore energized by current of opposite polarities, and only one of these portions is energized at any time.

As shown in the drawing, all parts are in the normal condition, that is, track relays T and T are energized; switch lever V is in its normal position 12; signal lever V is in its normal position m; switch W is in its normal position; sig nals S and S are indicating stop; relays H, K, P, L and w, control device F, and normal magnet mt are energized; relays H, v and R, reverse magnet Tr, and indicator lamp e are deenergized.

I will first trace the operation of the form of apparatus shown in Fig. 1. With signals S indicating stop, and with relay T energized, a pickup circuit is closed for energizing relay P, passing from terminal :t' of a suitable source of current not shown in the drawing, through contacts I! and is of signals S and 8, respectively, contact 20 of relay T and the winding of relay P to terminal 0 of the same source of current. A stick circuit is also closed for relay P, and is the same as the pick-up circuit just traced except that it includes the front point of contact 2| of relay P instead of contact 20 of relay T A pick-up circuit for relay L is closed, passing from terminal at, through contact 9 in its normal position, back point of contact 24 of relay v, contacts 25 and 215 and the winding of relay L to terminal 0. A stick circuit is also closed for relay L, passing from terminal at, through the front point of contact 21 of relay L, contacts 25 and 26 and the winding of relay L to terminal 0.

Switch control device F is energized in the normal direction by a circuit passing from terminal m, through the back point of contact I of relay 0, front point of contact 10 of relay L, device F, front point of contact I3 of relay L, and the back point of contact 8 of relay 1) to terminal 0;

Relay w, being controlled in multiple with device F, is also energized in the normal direction.

A circuit for energizing switch indication relay K by current of normal polarity is closed, passing from terminal at, through contact 3| of switch W in the normal position, winding of relay K, and contact 32 of switch W in the normal position to terminal 0.

Signal relay H is energized by its circuit passing from terminal as, through the back point of contact 1 of relay 1), front point of contact ll) of relay L, contacts H and ii of relay K, and the winding of relay H to terminal 0.

I will assume that, with all parts of the apparatus of Fig. 1 thus in their normal condition, the leverman desires to clear signal S to permit a trafllc movement to be made along track Y over switch W in the normal position. He will therefore move lever V to its r position, thus completing a circuit for operating signal S to the clear position, this circuit passing from terminal 33, through contact 34 of lever V contact 36 of relay H and the mechansm of signal S to terminal 0.

Signal S*-, upon being operated to the clear position, opens its contact l1, thereby deenergizing approach locking relay P. Relay P, upon becoming deenergized, permits its contact '25 to open and thereby deenergize relay L.

Upon the deenergizatlon of relay L, contact 21 of this relay will close at its back point, thereby completing a circuit for energizing indicator e, this circuit passing from terminal at, through the back point of contact 21 of relay L, front point of contact 28 and indicator e to terminal 0.

With relay L deenergized, the circuit previously traced for switch control device F will be open at the front points of contacts In and I3 of relay L, but a second circuit will now be completed for energizing device F in the normal direction, this circuit passing from terminal 0:, through contact 9 in the normal position, back point of contact H! of relay L, device F, back point of contact l3 of relay L, contact 29 in the normal position, and contact 30 to terminal 0.

With relay L deenergized, a second circuit will also be completed for energizing signal relay H passing from terminal 1', through contact 9'" in the normal position, back point of contact "I of relay L, contacts II and I2 of relay K, and the winding of relay H to terminal 0.

When the leverman desires to return signal S to the stop position, he will return lever V to its m position, thereby deenergizing the mechanism of signal S If at this time there is no train on approach section BC, relay P will become energized by its pick-up circuit previously traced.

If, however, there is a train on section BC, causing relay T to be deenergized, the thermal relay R will become energized by its circuit passing from terminal m, through contacts I! and I 8 of signals S* and S respectively, back point of contact 2| of relay P, and heater element 23 of relay R to terminal 0. Upon the lapse of the necessary period of time, contact 22 of relay R will close, and relay P will then become energized by a second pick-upcircuit which is the same as the pick-up circuit previously traced, except that it includes contact 22 of relay R instead of contact 2!) of relay T If the leverman does not return lever V to its m position until a train has passed signal S and entered detector section C-D, relay P will become energized by a third pick-up circuit which is the same as the pick-up circuit first traced except that it includes contact I9 of relay '1 instead of contact 20 of relay T.

I will next assume that all parts of the apparatus are again in the normal condition, and that the leverman desires to reverse switch W. He will therefore move lever V to its r position, thus causing relay 1) to become energized by its circuit which includes contact 33 of lever V With relay 1: energized, switch control device F will become energized by a reverse circuit which is the same as the normal circuit first traced except that it includes the front points of contacts I and 8 of relay 1) instead of the back points of these contacts. With device F thus energized by current of reverse polarity, motor G will move switch W to its reverse position.

Relay K will become deenergized during this movement of switch W and, upon completion of the operation of switch W, will become energized by current of reverse polarity through a reverse circuit which is the same as the normal circuit previously traced for relay K except that it includes contacts 3| and 32 of switch W in their reverse positions instead of their normal positions. During the time that relay K is deenerglzed, indicator lamp e will be energized by its circuit passing from terminal 13 of a second source of current not shown in the drawing, through the back point of contact 28 and indicator e, to terminal 0, which is common to both sources of current. The second source of current may be arranged to supply current of a slow pulsating characteristic in order to give a distinctive blinking indication by lamp e.

Relay w, being controlled in multiple with device F, will now also be energized in the reverse direction, and will therefore reverse its contacts 9 and 29. With relay v energized, and with contact 9" closed in the reverse position, a sec- 0nd pick-up circuit is now closed for relay L, passing from terminal as, through contact 9 in its reverse position, front point of contact 24 of relay 1), contacts 25* and 26", and the winding of relay L to terminal 0. Relay L is, however, already energized by its stick circuit previously traced.

With relay 1) energized, and with relay K energized by current of reverse polarity, relay H- will be deenergized, and relay 1-1 will be energized by its circuit passing from terminal 1:, through the front point of contact 8 of relay 0, front point of contact iii of relay L, contacts l4 and I5 of re ay K, and the Winding of relay H to terminal q When the leverman desires to return switch W to its normal position, he will return lever V to its n position thereby deenergizing relay 0 and causing the normal control circuit for device F to be completed as previou ly traced. Switch indication relay K will become deenergized during the movement of switch W to its normal position and, upon the completion oi the movement of switch W to its normal position. will become energized by current of normal polarity in its ergizing circuit first described.

1 will now assume that, with all parts of the apparatus again in the normalcondltion, the leverman clears signal S as p l jy traced. Relays P and L will therefore be fieenergized and relay to and control device F 31 be energized in the. normal direction throu h contacts 9" and 5w and back points of conlacts Ill and ill of re- L. 1 will also assume that, while signal S is clear, h maintainer, in order to do some work on the switch, or for some other reason, opens manual contact 5 at motor G and manually reverses switch W. Contacts 3| and 32 of switch W, being of the usual and well-known switch indication type which will open as soon as the operation of unlocking the switch-and-lock movement of switch W is begun, will cause relay K to be deenergized at the beginning of the unlocking operation of switch W, and will therefore cause relay H to be deenergized before the movement of switch W is begun. With relay I-I deenergized, the arm of signal 5 will return to its stop position.

If there is no train. on approach section B-C, relay P will become energized by its pick-up circuit, first traced, as soon as contact I! of signal S closes. With relay P energized, relay L will become energized by its pick-up circuit first traced.

With relay L energized, relay w and device F will again be energized, in the normal direction, through the back points of contacts I and B of relay 1) and the front points of contacts Ill and II! of relay L.

Relay K will become energized in the reverse direction, by the second circuit previously described for this relay, as soon as switch W occupies its reverse position and is locked in that position.

Although relay K is energized in the reverse direction, signal relay H will not become energized since the condition of relay K does not agree with the condition of relay 1), and relay H is therefore included in a circuit, both ends of which are connected to terminal 0. This circuit passes from terminal 0, through the back point of contact 8 of relay v, front point of con tact I3 of relay L, contacts I4 and 15 of relay K, and the winding of relay H back to the same terminal 0.

As soon as the maintainer is through working at switch W and closes contact '5, control device F, being energized by its first normal control circuit previously traced, will cause motor G to return switch W to its normal position. Relay K will again become energized in the normal direction as soon as the movement of switch W to its normal position, and the locking of switch W in that position, have been completed. Signal control relay IF will then become energized by its circuit previously traced, thereby causing signal S to be operated to its clear position.

It follows that, without any accompanying action by the leverman, switch W and signal S will be returned, after the maintainer again closes contact 5, to the conditions in which they agree with the positions of levers V al'h'i v as set by the leverman before the manual actuation of the switch by the maintainer.

I will next assume that all parts 01 he apparatus are again in the normal condition, and that the leverman again clears signal S as previously described. I will further assume that an eastbound train enters section B -C, d t t lire maintainer this, places signal S in its stop position by opening HJZQQ, and beginning to manually reverse switoh W, but w-rt'beioie relay P has had time to be en s mti by its circui which includes contact 22 of relay R, the maintainer again closes contact 5.

With relay P deenergized, relay L will also be deenergized. The second normal control circuit previously traced for device F through contacts 9'' and 29" and the back points of contacts l0 and I3 of relay L will therefore be complet d,

With control device F thus energized by current of normal polarity, motor G will return switch W to its normal position, if it has been moved away from that position.

As soon as relay P has become energized by the second pick-up circuit traced for this relay, including contact 22 of relay R, relay L will become energized by its pick-up circuit first traced.

With switch W returned to its normal position, relay K will become energized by its normal pickup circuit previously traced. With relay K energized, and with relay L energized, relay H will again become energized by its circuit first traced, thereby causing the arm of signal S to be operatcd to its clear position.

I will now assume that with switch W again in its normal position and with signal S in its clear position, the maintainer again opens contact 5 at motor G and reverses switch W by hand, as previously described, thereby causing signal S to indicate stop. I will further assume that while contact 5 is open and before relay L becomes energized, the leverman reverses switch lever V thereby causing relay 2; to become energized as previously described.

With relay L deenergized, relay w will still be energized in the normal direction by its circuit previously described, including contacts S and 29 in their normal positions, and the back points of contacts l0 and I3 of relay L. On account of the maintainer having reversed switch W, switch indication relay K will now be energized in the reverse direction, but signal relay H will not become energized since it is included in a circuit, both ends of which are connected with terminal 0, this circuit passing from terminal 0, through contact 30 contact 29' in its normal position, back point of contact l3 of relay L, contacts l4 and 15 of relay K, and the winding of relay H to the same terminal 0.

As soon as relay P has become energized on account of signal S" being returned to its stop position, contact 25 in the circuits for relay L will become closed, but the pick-up circuit first traced for relay L will be open at the back point of contact 24 of relay 0, and the second pick-up circuit for relay L will be open at the reverse point of contact 9 since relay w is energized in the normal direction.

If the maintainer now closes contact 5 of motor G, switch W will be returned to its normal position by motor G since mechanism F is energized in the normal direction, in multiple with relay w, by the circuit through contacts 9w and 29w in their normal positions, and the back points of contacts l0 and I3 of relayL.

Upon the completion of the operation of switch W to its normal position, relay H will become energized by the second circuit previously traced for this relay, including contact W in its normal position and the back point of contact ll) of relay L. The arm of signal S will thereupon be operated to the clear position.

If new the leverman returns signal lever V to its normal position m. rela; fiwin"fl[ mirdeenergizecl if relay ris still i ed, although ay P Worries energized. In order to close a D di-up circuit for relay L, the leverman must Ieturn lever V to its normal position, thereby deenergizing relay 1: and causing relay L to become energized by its pick-up circuit first traced.

As soon as relay L becomes energized, its stick circuit will be completed, and hence the leverman can now, by reversing lever V and th energizing relay 1), cause switch control device F to be energized by current of reverse polarity to cause motor G to reverse switch W.

I will next assume that all parts of the apparatus are again returned to their normal condition and that the leverman again clears signal S, and also that the maintainer again opens contact 5 at motor G and reverses switch W by hand, thereby causing signal 8 to be returned to the stop position. As soon as the arm of signal S reaches the stop position, relay P will again be energized by its pick-up circuit first traced. Relay P, upon becoming energized, will complete the pick-up circuit first traced for relay L which will thus also be energized.

I will further assume that after relay L becomes energized, the leverman reverses switch lever V thereby causingrelay v to become energized by its circuit previously described. Relay L, upon becoming energized by its pick-up circuit, will again close its stick circuit.

With relay L energized and with relay 1) energized, relay w and control device F will become energized in the reverse direction by their circuits previously traced through the front points of contacts 1 and 8 of relay 0 and the front points of contacts Ill and I3 of relay L. Signal relay H will now also be energized by its circuit previously traced, and hence the arm of signal S will be cleared by its circuit passing from terminal as, through contact 34 of lever V contact 35 of relay H and the mechanism of signal S to terminal 0.

If now the maintainer closes contact 5 of motor G, switch W will be retained in its reversed position on account of control device F being energized in the reverse direction, and the arm of signal S will be retained in the clear position.

In the apparatus modified as shown in Fig. 2, relays K and L are controlled as described in connection with Fig. 1. Normal control magnet m2 is energized by its circuit passing from terminal :10, through the back point of contact 31 of relay 1:, front point of contact l3 of relay L, and the winding of magnet 1m to terminal 0. Signal relay H is also energized by its circuit passing from terminal :0, through the back point of contact 31 of relay 2), front point of. contact l3 of relay L, contacts H and I2 of relay K, and the winding of relay H to terminal 0.

If the leverman clears signal S, relay P, which is controlled as shown in Fig. 1, will become deenergized due to the opening of contact I? of signal S. also be deenergized, thereby completing a second circuit for magnet 1m passing from terminal a: through contact 9 in its normal position has}; point of contact I3 of relay L, and the winding of magnet nn to terminal 0. A second circuit will also be completed for relay H, passing through terminal as, through contact 9 in its normal position, back point of c entact l3 of relay L, contact H and I2 of relay K, and the winding of relay H to terminal 0.

I will assume that all parts of the apparatus mcetimned TJ their normal condition, and that t rman then proceeds to reverse switch W by reversing switch lever V and thereby ener gizing relay 0. \With relay 0 energized, a circuit; will be completed for energizing reverse magnet rr, this circuit paw s from terminal as, through the front point 1 contact 37 of relay 1;, front point of contact l0 oi relay L, and the winding of magnet Tr to terminal 0. Mechani m M il therefore reverse switch W. Upon the comple- With relay P deenergized, relay 13m tion of the operation and locking of switch W,

relay K will become energized by its reverse circuit previously described in connection with Fig. I. With relay K energized in the reverse direction, relay H will become energized by its circuit passing from terminal at, through the front point of contact 31 of relay 1), front point of contact In of relay L. contacts l4 and I5 of relay K, and the winding of relay H to terminal 0.

If the maintainer opens the circuits for magnets 1m and T1 in some manner, such for example, as by removing the control wires for these magnets from the terminal posts of the magnets, the operation of the apparatus will be similar to that described in connection with Fig. 1 when the maintainer opens contact 5 adjacent motor G, and will therefore be readily understood by reference to the drawing without further detail description.

From the foregoing description and the accompanying drawing, it follows that, in apparatus embodying my invention:

A. If a maintainer opens the control or operating circuits for a switch while a signal governing traillc movements over the switch is clear, and if the maintainer then moves the switch by hand, the signal will be put to stop as soon as the unlocking operation of the switch has begun, and the signal for governing trafiic movements over the switch in its new position will remain at stop after the switch has been reversed.

B. If the maintainer moves the switch to a new position by hand, causing a signal governing traffic movements over the switch to be placed in the stop condition, and if the leverman then changes the position of the switch lever to agree with that of the switch before the auxiliary looking relay L becomes energized, the signal will still not clear although the position of the switch agrees with the position of its lever.

C. If the maintainer moves the switch to a new position by hand, causing a signal governing trafilc movements over the switch to be placed in the stop condition, and if the leverman then changes the position of the switch lever to agree with that of the switch, after the auxiliary locking relay L becomes energized a signal will be cleared for governing traffic movements over the switch in the position to which it has been operated by the maintainer. If the maintainer now closes the switch operating circuit, the switch will be retained in the position to which it was operated by the maintainer, and the corresponding signal will be retained in the clear condition.

D. If, after the maintainer moves a switch by hand, the leverman makes no change in the position of the levers, and if the maintainer then again closes the switch circuits, the switch and signal will be automatically returned to the condition in which they were before the maintainer reversed the switch by hand.

Although I have herein shown and described only two forms of interlocking control apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track including a switch, a locking relay, a master relay, manually controllable means for at times energizing said master relay, a polarized control relay, a normal energizing circuit for said polarized control relay closed by said master relay in its deenergize'd condition and by said locking relay in the energized condition, a reverse energizing circuit for said polarized control relay closed by said master relay in the energized condition and byLsaid locking relay in the energized condition, normal and reverse stick circuits for said polarized control relay closed by its own normal and reverse polar contacts respectively and by said locking relay in the deenergized con-- dition, a pick-up circuit for said locking relay closed by said polarized control relay in the normal energized condition and by said master relay in the deenerized condition, a second pickup circuit for said locking relay closed by said polarized control relay in the reverse energized condition and by said master relay in the energized condition, a stick circuit for said locking relay closed by one of its own front contacts and by tralfic conditions in said stretch when said traffic conditions are suitable for said switch to be operated, normal and reverse control circuits for said switch closed by said master relay in its deenergized and energized conditions respectively while said locking relay is in the energized condition, and normal and reverse retaining circuits for said switch closed by said polarized control relay in the normal and reverse condition respectively while said locking relay is deenergized.

2. In combination, a stretch of railway track including a switch, a locking relay, a manually controllable device having a normal and a reverse position, a polarized control relay, normal and reverse energizing circuits for said polarized control relay closed by said manually controllable device in its normal and reverse positions respectively and by said locking relay in the energized condition, normal and reverse stick circuits for said polarized control relay closed by its own normal and reverse contacts respectively and by said locking relay in the deenergized condition, a pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their normal positions, a second pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their reverse positions, a stick circuit for said locking relay closed by one of its own front contacts and by trafllc conditions in said stretch which are suitable for said switch to be operated, normal and reverse control circuits for said switch closed by said manually controllable device in its normal and reverse positions respectively while said locking relay is energized, and normal and reverse retaining circuits for said switch closed by normal and reverse polar contacts respectively of said polarized control relay while said locking relay is deenergized.

3. In combination, a. stretch of railway track including a switch, a locking relay, a manually controllable device having a normal and a reverse position, a polarized control relay, normal and reverse energizing circuits for said polarized control relay closed by said manually controllable device in its normal and reverse positions respectively and by said locking relay in the energized condition, normal and reverse stick circuits for said polarized control relay closed by its own normal and reverse contacts respectively and by said locking relay in the deenergized condition, a pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their normal positions, a second pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their reverse positions, a stick circuit for said locking relay closed by one of its own front contacts and by traffic conditions in said stretch which are suitable for said switch to be operated, and means controlled by said manually controllable device if said locking relay is energized or by said polarized control relay if said locking relay is deenergized for moving said switch between its extreme positions.

4. In combination, a stretch of railway track including a switch, a locking relay, a manually controllable device having a normal and a reverse position, a polarized control relay, normal and reverse energizing circuits for said polarized control relay closed by said manually controllable device in its normal and reverse positions respectively and by said locking relay in the energized condition, normal and reverse stick circuits for said polarized control relay closed by its own normal and reverse contacts respectively and by said locking relay in the deenergized condition, a pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their normal positions, a second pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their reverse positions, a stick circuit for said locking relay closed by one of its own front contacts and by traflic conditions in said stretch which are suitable for said switch to be operated, means controlled by said manually controllable device if said locking relay is energized or by said polarized control relay if said locking relay is deenergized for moving said switch from each of its extreme positions to the other, a signal for governing trafic movements over said switch, and means controlled by said manually controllable device if said looking relay is energized or by said polarized control relay if said locking relay is deenergizcd and also by said switch for clearing said signal.

5. In combination, a stretch of railway track including a switch, a locking relay, a manually controllable device having a normal and a reverse position, a polarized control relay, normal and reverse energizing circuits for said polarized control relay closed by said manually controllable device in its normal and reverse positions respectively and by said locking relay in the energized condition, normal and reverse stick circuits for said polarized control relay closed by its own nor mal and reverse contacts respectively and by said locking relay in the deenergized condition, a pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their normal positions, a second pick-up circuit for said locking relay closed by said manually controllable device and by a polar contact of said polarized control relay in their reverse positions, a stick circuit for said locking relay closed by one of its own front contacts and by traffic conditions in said stretch which are suitable for said switch to be operated, means controlled by said manually controllable device if said locking relay is energized or by said polarized control relay if said locking relay is deenergized for moving said switch from each of its extreme positions to the other, a normal and a reverse signal for governing traffic movements over said switch in its normal and reverse positions respectively, and means controlled by said manually controllable device if said locking relay is energized or by said polarized control relay if said locking relay is deenergized and also by said switch for clearing said normal or said reverse signal according as said switch is in its normal or its reverse position.

6. In combination, a railway track switch, a signal for governing traflic movements over said switch, a signal control device manually operable to clear said signal if said switch is in its normal position, a switch control device manually operable to a first or a second condition for setting said switch into operation toward its normal or its reverse position respectively, a second switch control device manually operable to a reverse position to remove said first switch control device from control of said switch to permit said switch to be manually actuated, a polarized switch control relay, means controlled by said first switch control device for energizing said polarized switch control relay by current of normal or reverse polarity according as said first switch control device is put into its first or its second condition respectively, and means controlled by said polarized switch control relay and by said signal for preventing storage of control of said switch by said first switch control device if while said signal is clear said second switch control device is operated to remove said first switch control device from control of said switch and if said switch is then manually actuated and if then said first switch control device is put into its second condition andsaid second switch control device is afterwards returned to its normal position.

7. In combination, a railway track switch, a polarized relay having normal and reverse polar contacts which when the relay is deenergized remain closed in the position corresponding to the last previous direction of energization of said relay, switch mechanism responsive to current of normal or reverse polarity for operating said switch to normal and reverse positions respectively, a manually operable device, a lock relay, means for energizing said lock relay controlled jointly by said polarized relay and said manually operable device, means controlled by traffic conditions adjacent said switch for retaining said lock relay in the energized condition only if said traffic conditions are suitable for said switch to be operated, circuits controlled by said manually operable device for energizing said switch mechanism by current of normal or reverse polarity in multiple with said polarized relay if said lock relay is energized, and circuits controlled by polar contacts of said polarized relay for retaining said switch in the position to which it was last operated if said lock relay is deenergized.

8. In combination, a railway track switch, a polarized relay having normal and reverse polar contacts which when the relay is deenergized remain closed in the position corresponding to the last previous direction of energization of said relay, switch mechanism responsive to current of normal or reverse polarity for operating said switch to normal and reverse positions respectively, locking means, manually controllable means cooperating with said polarized relay for energizing said locking means, means controlled by traffic conditions adjacent said switch for retaining said locking means in the energized condition if said traffic conditions are suitable e in multiple with said polarized relay under the energized condition of said locking means, and means controlled by polar contacts of said polarized relay for retaining said switch in the position to which it was last operated under the deenergized condition of said locking means.

9. In combination, a railway track switch, a polarized relay having normal and reverse polar contacts which when the relay is deenergized remain closed in the position corresponding to the last previous direction of energization of said relay, switch mechanism responsive to current of normal or reverse polarity for operating said switch to normal and reverse positions respectively, locking means, manually controllable means cooperating with said polarized relay for energizing said locking means, means controlled by traffic conditions adjacent said switch for retaining said locking means in the energized condition if said traffic conditions are suitable for said switch to be operated, manually controllable means for energizing said switch mechanism by current of normal or reverse polarity in multiple with said polarized relay under the energized condition of said locking means, and means controlled by polar contacts of said polarized relay for energizing said switch mechanism by current of normal or reverse polarity under the dee-nergized condition of said locking means.

10. In combination, a railway track switch, a contact, a second contact, a switch control device responsive to current of normal or reverse polarity to close said first or second contact respectively, switch mechanism responsive to current of normal or reverse polarity for operating said switch to normal and reverse positions respectively, locking means, manually controllable means cooperating with said first and second contacts for energizing said locking means under given traflic conditions adjacent said switch, manually controllable means for energizing said switch mechanism and said switch control device by current of normal or reverse polarity under the energized condition of said locking means, and means controlled by said first and second contacts for energizing said switch mechanism by current of normal or reverse polarity under the deenergized condition of said locking means.

11. In combination, a railway track switch, a contact, a second contact, a switch control device responsive to current of normal or reverse polarity to close said first or second contact respectively, switch mechanism responsive to current of normal or reverse polarity for operating said switch to normal and reverse positions respectively, locking means, manually controllable means cooperating with said first and second contacts for energizing said locking means if traific conditions adjacent said switch are suitable for said switch to be operated, manually controllable means for energizing said switch mechanism and said switch control device by current of normal or reverse polarity under the energized condition of said locking means, and means controlled by said first and second contacts for energizing said switch mechanism and said switch control device by current of normal or reverse polarity under the deenergized condition of said locking means.

HOWARD A. THOMPSON. 

